Mask process correction method comparison and study: CD-SEM box versus standard correction method

With continuous shrinking technology nodes, the error tolerances for mask CD (critical dimension) becomes tighter and tighter since mask errors are passed on downstream and might even be amplified at wafer level. Therefore, high accuracy MPC (Mask Process Correction) models are imperative. Besides the mask model, the MPC algorithm for the input layout also has a critical influence on mask quality. This paper studies and compares two methods of MPC correction: a new method, introducing a correction algorithm based on the CD-SEM box is compared to the standard method that measures EPE (edge placement error) only at the center of an edge. Under which condition the EPE measurement method for MPC correction by the CD-SEM box method should be applied is discussed and its influence on the correction accuracy of small CD patterns is demonstrated.